Catalytic converter overheating protection

ABSTRACT

A temperature-monitoring device in a catalytic converter for use in an exhaust gas decontamination system for an internal combustion engine (e.g. a motor vehicle internal combustion engine), for monitoring the catalyst used in the converter against overheating, by indicating the attainment of a predetermined temperature in the converter and/or automatically controlling a separate arrangement for controlling the supply of exhaust gas to the converter, comprises an elongated heatexpandable element supported within the converter, the expansion of said element caused by said predetermined rise in temperature causing the operation of a switch means supported adjacent said element, said switch means, when operated, actuating a warning indicator means and/or said separate arrangement.

United States Patent 1191 Lamprecht CATALYTIC CONVERTER OVERHEATING PROTECTION [75] Inventor: Rudolf Lamprecht, Russelsheim am Main, Germany [73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Sept. 4, 1973 [21] App]. No.: 394,103

[30] Foreign Application Priority Data 1451 Sept. 10, 1974 3,412,236 11/1968 Hild et al. 337/394 Primary ExaminerHarold Broome Attorney, Agent, or Firm-Peter A. Taucher [57] ABSTRACT A temperature-monitoring device in a catalytic converter for use in an exhaust gas decontamination system for an internal combustion engine (e.g. a motor vehicle internal combustion engine), for monitoring the catalyst used in the converter against overheating, by indicating the-attainment of a predetermined temperature in the converter and/or automatically controlling a separate arrangement for controlling the supply of exhaust gas to the converter, comprises an elongated heat-expandable element supported within the converter, the expansion of said element caused by said predetermined rise in temperature causing the operation of a switch means supported adjacent said element, said switch means, when operated, actuating a warning indicator means and/or said separate arrangement.

2 Claims, 8 Drawing Figures PATENTEUSEPI o 1914 SHEET 1 OF 4 km Mm MW PAH-1m n SEP 1 01974 SHEET 2 or 4 PATENTED v 3.835.433

SHEET 3 [1F 4 v CATALYTIC CONVERTER OVERHEATING PROTECTION SPECIFICATION This invention relates to a monitoring device for protection against overheating, either automatically or by indicating the attainment of a predetermined temperature, in catalytic converters (reactors) for motor vehicle internal combustion engines, or other exhaust decontamination systems.

When exhaust decontamination systems, such as catalytic converters or reactors, are used in internal combustion engines care must be taken that the decontamination system is not overheated. The danger of overheating is especially great if a spark plug in the engine fails. Once a certain temperature is exceeded within the converter, the mass of catalyst in the catalytic converter is destroyed by the heat therein.

An object of the present invention is therefore to produce a simple and reliable monitoring device which warns the driver of the vehicle and/r automatically switches off the exhaust decontamination system when overheating occurs. According to the basic concept of the invention this object is achieved by installing a temperature-responsive element in a catalytic converter, this element having a relatively great coefficient of thermal expansion and working in conjunction with a switch which actuates a warning indicator and/or can be arranged to control or divert the exhaust gases supplied to the converter from entering the converter.

The temperature-responsive element can be a metallic expansion rod embedded in the catalyst material and preferably surrounded by the catalyst material. By

securely embedding the expansion rod in the catalyst mass there is no time delay because of heat transmission, so that the response time of the monitoring device according to the invention is kept to a minimum.

The method of functioning of the monitoring device in accordance with the invention therefore is based on the known effect of elongation of a metallic rod when heated. Since the change in length Al of the rod when heated is all the greater the greater the rod length before heating, a further feature of the invention is that the metallic expansion rod is made long enough to extend through the entire width of the catalytic converter, so that said rod is surrounded by the catalyst material over the greater part of its length. The correspondingly large change in length Al thus achieved is important for a safe switching of the device.

Since the (permissible) temperature difference which occurs when the expansion rod is heated has a corresponding influence on the magnitude of the change in length this should be chosen as great as possible. The greater the temperature difference the smaller the inertia of the device.

Further features of the invention reside in that the metallic expansion rod is fixed at one end to the converter housing and the other axially movable end is used to operate the switch, this free end of the metallic expansion rod being connected to a flexible diaphragm type plate disc this being thus displaceable axially with the rod and the diaphragm type plate disc seals off a hole in the converter housing through which passes the free end of the expansion rod.

The diaphragm type plate disc can be rivetted to the metallic expansion rod or detachably connected thereto. The usefulness of the latter alternative is that the expansion rod can then be easily installed in, and dismantled from, the converter housing.

Of course when heated the rod expands at both ends by the same amount. However in order to bring about the situation in which the total amount of rod expansion is used to close the gap between the switch and the free end of the expansion rod, another feature of the invention resides in that the switch to be operated by the metallic expansion rod is located on the free end of a bow member which crosses over the converter housing, and that said bow member is connected at its other end to the fastening point of the expansion rod to the converter housing, the end of the expansion rod which is fixed to the converter housing also serving to connect the bow member to the converter housing.

Because the bow member must have on the one hand a certain amount of strength and on the other hand remain more or less uninfiuenced by the temperatures which occur in the catalytic converter, it is necessary to make the bow member of metal and to fix an asbestos plate to the side of the bow member which faces the converter. The bow member is given a somewhat semicircular arched section and is connected to the asbestos plate only at its two flange-like bent edges. In this way a somewhat semicircular hollow space is formed between the bow member and the asbestos plate, which also has a heat insulating effect. Moreover the above design of the bow member increases its moment of resistance, which has a favourable effect on its bending resistance and as a consequence of this on the accuracy of the monitoring device according to the invention. ln this connection it is also useful if the middle of the free end of the bow member is provided with a hole through which passes the free end of the expansion rod.

The warning and/or switching off device actuated by the expansion rod in accordance with the invention can be operated by any known suitable means, e.g., by hydraulic or pneumatic means. According to the invention, however, electric indicating instruments are preferred because of their obvious advantages, in that when the switch is operated by the expansion rod an electric circuit is closed in which is situated a warning lamp or similar indicating instrument. The expansion rod can either be purely mechanical, i.e., only provides the necessary force for closing the switch, or can itself be a component of the warning circuit, in that a contact made of suitable metal is pressed on to the end of the expansion rod. The last-mentioned alternative makes it easy to adjust the switch, in that the switch contact which touches the expansion rod is made springy and can be adjusted with respect to its distance from the end of the expansion rod, for example, by means of an adjusting screw with lock nut.

According to another feature of the invention it is especially useful if the circuit of the warning indicator is so designed that when the maximum permissible temperature in the catalytic converter is exceeded a first closed electrical circuit including the expansion rod is interrupted by a microswitch operated by the elongation of the expansion rod, said interruption causing a second circuit (operating circuit) to become closed, which in turn puts into operation the warning indicator. The advantage of this idea is that if the first circuit is wrongly interrupted, whether by damage to the first electrical circuit or breakage of the expansion rod, the warning indicator still operates.

These and other features of the invention will be readily apparent from the following specification and drawings, in which:

FIG. 1 shows a partial cross-sectional view of a catalytic converter containing a monitoring device according to the invention, and suitable for use in controlling the exhaust emissions from a motor vehicle internal combustion engine;

FIG. 2 shows an enlarged view of a portion of FIG. 1;

FIG. 3 shows a cross-sectional view of a portion of FIG. 2, taken along the line IIIIII in FIG. 2;

FIG. 4 shows a modification of a portion of FIG. 2;

FIG. 7 shows a portion of FIG. 2 with parts broken v away, and showing an inserted feeler gauge; and

FIG. 8 shows the same portion as shown in FIG. 7, in which the feeler gauge is withdrawn by a predetermined distance.

As can'be seen especially in FIGS. 1 and 2, a catalytic converter according to the invention, suitable for mounting on a motor vehicle internal combustion engine in order to control the emissions in the exhaust gases therefrom, consists of a catalyst mass 10, which is enclosed by a housing 11 adapted to be connected to the exhaust system of an internal combustion engine so that the exhaust gases produced during the operation of said engine can be passed through the enclosed catalyst mass. A metallic expansion rod 12 passes through the entire width of the catalyst mass 10, so as to be completely enclosed by the catalyst mass. In this way the heat produced in the catalyst mass 10 can penetrate directly into the metal of the expansion rod 12 without any time delays produced as a result of heat transmission between the parts 10 and 12 via any neighbouring parts of the converter.

On each side of the housing 11 there is an aperture 13, 14, through which the respective end 15, 16 of the expansion rod 12 projects. One of the ends 16 of the expansion rod 12 is fixed by means of a nut 20 to an outer housing 17 surrounding the housing 11, said outer housing being welded to the housing 11 at points 18, 19. The other end 15 of the expansion rod is connected in gastight relationship to a flexible diaphragmtype circular plate disc 21 whose peripheral edge 22 is welded to the outer housing 17 to seal off the opening 23 provided therein for the expansion rod 12.

The connection of the expansion rod 12 to the diaphragm-like plate disc 21 is as shown in FIGS. 1 3 and comprises, as shown in FIG. 2 a rectangular metal piece which is inserted into a corresponding cross recess 24 in the rod 12. A central hole 26 in the disc 21 for receiving the expansion rod 12 is as can be seen in FIG. 3 slotted at two places 27 so that the contour of the rectangular piece 25 mates with the slotted apertures 27 in disc 21. To connect the rod 12 to the disc 21, the expansion rod 12 is first inserted through the opening 26 in the disc 21 with the rectangular piece 25 aligned with the apertures 27 until the rectangular piece 25 is inside the outer housing 17. The expansion rod 12 is then rotated through 90, the hole 26 sealed off with a washer 28 and the fastening of the rod 12 to the disc 21 completed by means of a nut 29.

Alternatively, in the embodiment shown in FIG. 4, the expansion rod 12 can be permanently fixed to the disc 21 by rivets 30. r I

As can be further seen in FIGS. 1 and 2, the outer housing 17 is spanned on one side by a bow member 31 which has one end 32 bent down like a fishplate on to the outer housing 17 and secured thereto by means of the nut 20 on the expansion rod 12. The surface of the bow member 31 adjacent the outer housing 17 is protected from distortion and heat by means of an asbestos plate 33 as can be seen in FIGS. 1 and 6. For this purpose the asbestos plate 33 is rivetted to the edges 34 of the semicircular-sectioned bow member 31 (FIG. 6), which edges are bent round like flanges.

The other end of the bow member 31, designated by 36, is designed as a switch housing. This housing 36 is so designed that it can accommodate an insulated terminal plug 37, an adjustment screw 38 with lock nut 39 and locking plate 40, a springy contact arm 41 carrying a contact terminal 42 and an insulated adjustment piece 43, a control hole 44 (FIG. 5) and fastening screws 45 for a guide bearing plate 46 (FIG. 5). The guide bearing plate 46 is so designed that it locates the bow member 31 relative to the end of the expansion rod 12 and also serves as an underpart of the switch housing. A protective ring 47 attached to the plate 46 is intended to prevent fouling of a guide hole 48 in plate 46, through which hole passes the end of rod 12.

In FIG. 1 it can be seen that the expansion rod 12 is electrically connected with the housing 17, and forms part of an electric circuit 49, which also includes the springy contact arm 41, a warning device 50 (e.g., a warning lamp) and a source of electrical power 51, such as the battery of the vehicle on which the catalytic converter is installed.

When the catalytic converter containing the monitoring device of the invention is installed on the engine of a motor vehicle, and the engine is operating, the exhaust gases from the engine pass through the catalyst mass 10, and the expansion rod 12 elongates as a result of being heated, and presses the diaphragm like plate disc 21 towards the guide plate 46. Any movement of the rod taking place in the opposite direction is compensated by the corresponding movement of the bow member 31 due to the connection of end 32 to the end 16 of the rod 12. The switching distance thus would remain unchanged as a result of such a movement of end 16. When a predetermined temperature of the rod is reached, a contact piece 52 secured in the end 15 of the expansion rod, touches the terminal 42 of the springy contact arm 41, so closing the electrical circuit and actuating the warning device 50. If the expansion rod 12 elongates further, because the converter temperature is rising above the predetermined temperature the spring contact 41 is bent back over the adjusting screw 38. When the converter cools down again, the expansion rod 12 contracts, the spring contact 41 returns to its previous position and, when the terminal 42 ceases to contact the contact piece 52, the electrical circuit is disconnected and the warning device 50 is deactuated. If desired, the warning device can also incorporate a control mechanism for controlling or diverting the flow of exhaust gases through the converter automatically in response to the monitoring device.

To facilitate easy adjustment of the switchdescribed above, a control hole 44 is provided in housing 36. As FIG. 7 shows, a feeler gauge 53, which consists of handle 54, and a measuring screw 55, the end of which screw is inserted through the control hole 44 and the measuring screw 55 so adjusted that the contact terminal 42 on the springy contact arm 41 rests against the contact piece 52 of the expansion rod 12. i

As FIG. 8 shows a solid measuring block 56 is now placed on the handle 54, the thickness of this block being equivalent to the increase in length of the expansion rod 12 that occurs when the predetermined temperature of the rod is reached. If the feeler gauge 53 is connected in circuit electrically with a test lamp and the plug contact 37, then the adjusting screw 55 is adjusted until the lamp goes on. The proper setting for the spring contact arm 41 has been found by adjusting the adjustment screw 38 in the housing 36 until the test lamp goes out again.

The locking plate is swung over the control hole 44 after the setting has been made (FlG. 2), the lock nut 39 tightened, and a flange 57 of the locking plate 40 bent against a hexagonal side of the lock nut 39 (FIGS. 2 and 5). The insulated adjustment piece 43 is an insulating plastics material piece formed round the springy contact arm 41 (see also FIG. 5, the dot-dashed contour). The springy contact arm 41 is pre-formed so that it presses against the adjustment screw 38.

Thus this invention provides a temperaturemonitoring device in a catalytic converter for use in an exhaust gas decontamination system for an internal combustion engine, for protection of the catalyst used in the converter against overheating.

I claim:

1. A temperature-monitoring device for use in a catalytic converter housing containing a mass of catalytic material, said converter adapted to be installed on a motor vehicle for use with an internal combustion engine with said temperature-monitoring device comprising: a rod that extends through the catalytic converter housing and is embedded within the mass of catalyst material, a retaining plate positioned adjacent said converter at the area, through which the rod extends and which surrounds a portion of the converter and is further located a distance away from the converter in other areas to thereby provide a space between the retaining plate and said converter in these areas, insulation means attached to said retaining plate to insulate the retaining plate from the converter so that heat generated by the converter will not influence the expansion and contraction of the retaining plate or the rod attached thereto, said rod having support means that extends outside the converter and through said retaining plate, to which a fastening means is secured to maintain said rod in locked relationship within the converter and to the retaining plate at one end, said rod further extends through said converter at the other end and is held in fixed relationship thereto, by a diaphragm and fastening means that holds said rod in proper relationship within the converter, said diaphragm also seals the end of the converter through which the rod extends, yet provides a means of allowing the rod to expand upon being heated by the reaction of the catalyst material, and switch means, connected to said retaining plate at the end adjacent the diaphragm by a switch support means that includes said retaining plate and an elongated member extending over, and spaced apart from the exterior surface of the converter with one end of said elongated member being connected to the retaining plate a distance from said converter on the side in which the metal diaphragm is located with the end of said retaining plate supporting said switch means a distance away from said rod whereby the expansion of said rod caused by a predetermined rise in temperature within said mass of catalyst material causes said rod to expand toward said switch means and after a set predetermined distance of expansion to close contacts on said switch means to activate a warning indicator means connected to said switch means.

2. A temperature-monitoring device for use in a catalytic converter containing a catalyst material said converter adapted for use on an internal combustion engine, said temperature-monitoring device comprising: an elongated heat-expandable rod that extends through the catalytic converter housing and is embedded within the mass of catalyst material, a retaining plate positioned adjacent said converter at the area, through which the heat-expandable rod extends and which surrounds a portion of the converter and is further located a distance away from the converter in other areas to thereby provide a space between the retaining plate and said converter in these areas, insulation means attached to said retaining plate to insulate the retaining plate from the converter so that heat generated by the converter will not influence the expansion and contraction of the retaining plate or the heat-expandable rod attached thereto, said heat-expandable rod having support means that extends outside the converter and through said retaining plate, to which a fastening means is secured to maintain said heat-expandable rod in locked relationship within the converter and to the retaining plate at one end, said heat-expandable rod being further held in fixed relationship within the converter by an expandable metal diaphragm and fastening means that holds said heat-expandable rod in proper relationship within the converter, and also seals the end of the converter through which the heat-expandable rod extends, but provides a means of allowing the rod to expand upon being heated by the reaction of the catalyst material, said metal diaphragm having slotted means therein that permits easy assembly thereto of the heat-expandable rod, and switch means, connected to said retaining plate at the end adjacent the metal diaphragm by a switch support means that includes said retaining plate and an elongated member extending over, and spaced apart from the exterior surface of the converter with one end of said elongated member being connected to the retaining plate a distance from said converter on the side in which the metal diaphragm is located with the end of said retaining plate supporting said switch means a distance away from said heatexpandable rod whereby the expansion of said heatexpandable rod caused by a predetermined rise in temperature within said mass of catalyst material causes said rod to expand toward said switch means and after a set predetermined distance of expansion to close contacts on said switch means to activate a warning indicator means connected to said switch means. 

1. A temperature-monitoring device for use in a catalytic converter housing containing a mass of catalytic material, said converter adapted to be installed on a motor vehicle for use with an internal combustion engine with said temperature-monitoring device comprising: a rod that extends through the catalytic converter housing and is embedded within the mass of catalyst material, a retaining plate positioned adjacent said converter at the area, through which the rod extends and which surrounds a portion of the converter and is further located a distance away from the converter in other areas to thereby provide a space between the retaining plate and said converter in these areas, insulation means attached to said retaining plate to insulate the retaining plate from the converter so that heat generated by the converter will not influence the expansion and contraction of the retaining plate or the rod attached thereto, said rod having support means that extends outside the converter and through said retaining plate, to which a fastening means is secured to maintain said rod in locked relationship within the converter and to the retaining plate at one end, said rod further extends through said converter at the other end and is held in fixed relationship thereto, by a diaphragm and fastening means that holds said rod in proper relationship within the converter, said diaphragm also seals the end of the converter through which the rod extends, yet provides a means of allowing the rod to expand upon being heated by the reaction of the catalyst material, and switch means, connected to said retaining plate at the end adjacent the diaphragm by a switch support means that includes said retaining plate and an elongated member extending over, and spaced apart from the exterior surface of the converter with one end of said elongated member being connected to the retaining plate a distance from said converter on the side in which the metal diaphragm is located with the end of said retaining plate supporting said switch means a distance away from said rod whereby the expansion of said rod caused by a predetermined rise in temperature within said mass of catalyst material causes said rod to expand toward said switch means and after a set predetermined distance of expansion to close contacts on said switch means to activate a warning indicator means connected to said switch means.
 2. A temperature-monitoring device for use in a catalytic converter containing a catalyst material said converter adapted for use on an internal combustion engine, said temperature-monitoring device comprising: an elongated heat-expandable rod that extends through the catalytic converter housing and is embedded within the mass of catalyst material, a retaining plate positioned adjacent said converter at the area, through which the heat-expandable rod extends and which surrounds a portion of the converter and is further located a distance away from the converter in other areas to thereby provide a space between the retaining plate and said converter in these areas, insulation means attached to said retaining plate to insulate the retaining plate from the converter so that heat generated by the converter will not influence the expansion and contraction of the retaining plate or the heat-expandable rod attached theReto, said heat-expandable rod having support means that extends outside the converter and through said retaining plate, to which a fastening means is secured to maintain said heat-expandable rod in locked relationship within the converter and to the retaining plate at one end, said heat-expandable rod being further held in fixed relationship within the converter by an expandable metal diaphragm and fastening means that holds said heat-expandable rod in proper relationship within the converter, and also seals the end of the converter through which the heat-expandable rod extends, but provides a means of allowing the rod to expand upon being heated by the reaction of the catalyst material, said metal diaphragm having slotted means therein that permits easy assembly thereto of the heat-expandable rod, and switch means, connected to said retaining plate at the end adjacent the metal diaphragm by a switch support means that includes said retaining plate and an elongated member extending over, and spaced apart from the exterior surface of the converter with one end of said elongated member being connected to the retaining plate a distance from said converter on the side in which the metal diaphragm is located with the end of said retaining plate supporting said switch means a distance away from said heat-expandable rod whereby the expansion of said heat-expandable rod caused by a predetermined rise in temperature within said mass of catalyst material causes said rod to expand toward said switch means and after a set predetermined distance of expansion to close contacts on said switch means to activate a warning indicator means connected to said switch means. 